TPU polymers are typically made by reacting a hydroxyl terminated polyether or polyester, a chain extender and an isocyanate compound. Various types of compounds for each of the three reactants are disclosed in the literature. The TPU polymers made from these three reactants find use in various fields where products are made by melt processing the TPU and forming into various shapes by processes such as extrusion and molding. An important use of TPU is in the area of making melt spun elastic fibers, known as Spandex. The TPU fibers can be combined with other natural and synthetic fibers to make clothing and several other consumer and industrial products.
TPUs is a segmented polymer having soft segments and hard segments. This feature accounts for the excellent elastic properties of TPU. The soft segment is made up of the hydroxyl terminated intermediate, usually a polyether or polyester. The hard segments are made up of the chain extender glycol and the isocyanate.
U.S. Pat. No. 5,959,059 discloses a TPU made from a hydroxyl terminated polyether, a glycol chain extender and a diisocyanate. The TPU is useful for making fibers, golf ball cores, recreational wheels as well as other uses.
One of the deficiencies of previous known TPU fibers is their low temperature resistance. Temperature resistance is important if one wishes to make an article such as clothing by combining the TPU fibers with synthetic fibers, such as polyester fibers. These synthetic fibers must be dyed and heat set at high temperatures to prevent the clothing made from them from shrinking during washing and drying cycles. For this reason, lower temperature TPU fibers have found application in combination with natural fibers such as cotton, which do not require the high temperature heat setting treatment.
A higher temperature resistant TPU would also be desirable in fabric coating applications. One fabric coating application is in clothing where a TPU liner can be used with a fluro polymer coating which is usually heated after application to the fabric to dry and cross-link the fluro polymer. The TPU needs to withstand this heating process.
TPU polymers can also be used in applications where anti-static properties are important, such as packaging for sensitive electronic parts.
U.S. Pat. Nos. 6,140,405; 5,863,466; 6,284,839; 5,574,104; 5,159,053; 6,207,361 and 6,197,486 all disclose TPU for use in making articles with anti-static or electrostatic dissipative properties.
Another important property of the TPU for applications of this invention is its moisture vapor transmission (MVT) properties. A TPU's MVT properties is important in applications such as fabric coating, fibers, roofing membranes, house wrap and other applications. A high MVT TPU will allow moisture vapor to escape but will not allow liquid water to penetrate. This feature allows clothing to be more comfortable and to keep building structures dry.
A TPU having the properties of high temperature resistance, high MVT and anti-static properties would be highly desirable and would allow enhanced performance in products such as fibers, fabric coating, house wrap, roofing products, and clothing.